Fire control pilot



April 15, 1952 c. R. BowLAND Erm.

FIRE CONTROL PILOT 3 Sheets-Sheet l Filed 001;. 30, 194'? April 15, 1952 c. R. BowLAND ETA. 2,593,004

FIRE CONTROL PILOT Filed O01). 30, 1947 3 Sheets-Sheet 2 April 15, 1952 c. R. BowLAND ETAL 2,593,004

FIRE CONTROL PILOT 3 Sheets-Sheet 5 Filed OCT.. 50, 194'? Patented Apr. 15, 1,952

FIRE CONTROL PILOT Charles Richard Bowland and Linville H. Crick, Jr., Spring Valley, Ill., assignors to Sampsel Time Control, Inc., Spring Valley, Ill., a corporation of Illinois Application October 30, 1947, Serial No. 783,188

4 Claims.

The present invention relates to an electrical timing mechanism and is concerned more particularly with the provision of a periodically operated power driven switch for piloting the operation of central equipment for fuel burning heating plants.

In order to maintain minimum fire conditions in a coal burning automatically fed system, particularly during mild weather conditions when heat demand signals are infrequent or widely spaced in point of time, it is necessary Ato operate the fuel feeding and firing functions at predetermined minimum intervals in order to prevent the fire from dying out. These minimum conditions of operation will vary in accordance with the quality of the coal used, having particular reference' to its re holding characteristics; and in order to prevent over-heating discomfort, the minimum fire conditions should be kept critically conned to marginal fire sustenance. It is, therefore, a principal object of the present invention to provide a firing piloting mechanism which lends itself conveniently to adjust for maintaining minimum fire conditions under a range of operating intervals, so as to be adaptable to the different characteristics of coal, viz., fire sustaining, coking, etc.

In the performance of electrical circuit supervision of automatic fuel burning systems, even where there is contemplated a supervisory circuit of low voltage, it is highly desirable to mim'- mize contact arcing effects such as customarily result from slow cam actuated contact operations. Ihese undesirable consequences are prevented by designing contact breakers so that they operate instantaneously causing separation under snap action conditions.

Itis, accordingly, another object of the present invention to provide circuit piloting apparatus which may be manufactured and assembled economically and precisely while affording instantaneous contact action to minimize burning and arcing during the numerous control functions incident to continuous heating regulation.

In conjunction with stoker mechanisms, there is sometimes provided certain auxiliary safety adjuncts such as those for denoting depletion of coal in the hopper or overloading of the feed screw due to obstruction or other causes. In connection with these special supervisory safety features. it is contemplated herewith to provide a central piloting apparatus which may be produced in accordance with the already declared obiectives. and which will embrace structural controls.

For a more comprehensive understanding of the present invention, reference will now be had to the accompanying drawings and to the following detailed specification in which like reference characters designate corresponding parts throughout and in which,

Fig. l is a front elevational view of a principal housing cabinet in which is contained the re piloting apparatus according to the present invention as well as control circuit relay and transformer devices,

Fig. 2 is a side elevational view of the flre pilot control mechanism enlarged to reveal the general assembly through its mounting panel board,

Fig. 3 is a plan view taken approximately on line 3 3 of Fig. 2,

Fig 4 is a front elevational view of the fire pilot control mechanism featured in Fig. 1 with the frontal control panel thereof removed,

Fig. 5 is a transverse sectional view taken approximately on line 5 5 of Fig. 4.

Fig. 6 is a further enlarged front elevational detail view of the timing distributer disk and its associated drop-off contacts and,

Fig. 7 is a schematic circuit diagram of a representative field installation wherein a fire pilot control mechanism according to the present invention is installed to regulate a coal fed hot air heating plant.

Attention will now be directed to a structural description of the apparatus shown in the accompanying drawings. Reference numeral II designates a metallic box provided with a hinged cover I2 for protectively enclosing the re pilot and auxiliary apparatus generally designated I3 and I4. The auxiliary apparatus I4 consists simply of an electrically non-conductive panel member I5 on which is mounted a supervisory relay which is energized by the low voltage circuit, later to be described in conjunction with Fig. 7, as well as a voltage reducing transformer for establishing the operating voltage employed in the supervisory circuit by reduction of domestic line service voltage.

A principal panel member I 6 is secured as by the screws I1 to the piece II of the housing or box. and. the spawn. in said box is also laterally divided by a partitioning member I8 suitably anchored.

In order to make the apparatus manifestly understandable to homo-holders and others not speciali ar'cv'aioted with wiring systems the secondarv panels I 5 and I9 are engraved with instruction legends as will be readily discernible from Fig. l revealing not only the adjustment and regulatory data, but also indicating in accordance with the predetermined color coding plan the wiring terminals, adjustment periods and other. The secondary panel I9 (see also Figs. 2, 3 and 5) is a rectangle of dielectric material upon which the nre piloting mechanism is totally supported upon four mounting bolts 2|. These bolts are secured as by riveting at 22 to a steel plate 23, and in addition, they also give support to two strips or plates of insulating material designated 24 and 25, best seen in Fig. 4.

Strip 24 mounts a stationary spring contact member 25, one end of which is bent-as at 26 and spring tensioned to follow `an outermost circular path of the distributor disk 21 and is also provided with an electrical contracting tongue 28 for communicating with the electrical terminal screw 29, Figs. l and 2. The electrical connection between tongue 28 and screw 29 is made through a conductive strip 3|, Fig. 2.

The other insulating plate 25 in a similar fashion carries three stationary contact blades designated 32, 33 and 34 which follow respectively an outermost, an intermediate, and an innermost circular path of the distributor disk 21 as the latter is rotated by a synchronous motor and gear' reduction system contained in the housing 35'so designed as to impart to the shaft 36 one cycle of'rotation perv hour. The construction of the motor-and gear reduction apparatus form no'part of the present invention and may be any of vseveral commercial assemblies manufactured and 'wellknown in the general eld of time regulated movements.

The shaft 33 extends through a journal 31 f supported in the flange 38 ofthe motor housing disk and carries a coupling spring 39 which serves as a resilient clutch to drive a spur shaft 4I with which it is in axial alignment.

Spurshaft'lil is threaded as at 42 and thereat receives an insulated 'button 43 whereby it may be rotated in a clockwise direction carrying with it; spring 39 vwhoseconvolutions vunder such conditions slip upon shaft 36. When clockwise rotation is initiated at shaft 36, however, the convolutionsof spring 39 are caused to be constricted through theA frictional engagement with said shaft, so that no slippage may occur and so that this motion is transmitted tothe vspur shaft 4i.

As will be noted, particularly from Fig. 5, spur shaft 4l is formed with several varying diameters at its largest one of which its periphery is iluted so as jto effect keying with the distributor disk 2-1, and as'a result of which said disk rotates integrally with the spur shaft 4i. During manufacturing assembly, the shaft is split longitudinally throughout a limited distance as indicated at 44, in orderto afford marginal compressibility during the driving engagement with the disk 21. At anpintermediate shouldered diameter designated' 45v shaft 4I passes through the support panel i9 whereby spaced relationship with the posterior contacting mechanisms is infallibly insured.

"Io the steel'plate 23 there is secured as by wedging orv over-spinning as at 45, a journal sleeve 41 whose foremost flange 48 confines the rotatable contact regulators 49 and '5| which are tensioned against free rotation by a radially split tensioning spacer 52, a tangential arm 53 of which is anchored as by riveting 54 to the ondary panel I9, while the nethermost regulator 49 oppositely but correspondingly is provided with a forwardly extending arm 53 also forked as` at 55 protruding through the arcuate slot 59, Fig. l in opposite symmetry.

The forked protrusions are so constructed to give tensioned support to the electrically insulated thumb knobs Sl and 62 which may carry markings engraved on a cylindrical element of each, whereby to identify adjustment or placement in respect to their related engravings 63 and 64 which denote the period of operation respecting their functions.

Noting particularly the construction of each regulator, it will now be observed that the pilot regulator 5i is provided with an offset arm 65 to which is secured as by riveting 66 a movable contact spring 61, Fig. 6. Correspondingly, regulator 49 is provided with an offset arm 58 to which is secured by the rivets E55 a spring contact 69, contacts 61 and 69 being both so disposed as to follow in the outermost of the circular paths already referred to earlier in the description.

As the regulators are rotated through the limited arcs'of travel afforded by the arcuate slots 51 and 59 of the panel i9, they carry with them respectively-the springs 61 and 69 and establish a spaced relationship, spring S'l-with respect to its associated stationary spring 25 and spring 59 with respect to its three-associated contact springs 32,33 and 34. Thespaced relationship between each one of the movable wiper-springs 61 and 63 with their related stationary wiper springsconstitutes the establishment of operating period, respecting control function as the bridging segments of the distributor disk -21 passed beneath them in a counter-clockwise direction as viewed in Figs. 4 and'6.

The distributor disk 21 may be made of fiber, Bakelite ofany other insulation material andA on its forward face is divided into four equal quadrants separatedby theradial surface notches 1I. On each quadrant `it carries an electrically conductive segment, one of which 'designated 12 is an hourly period segment and `is of 'sufcient radial width to have engagement Vwith all three of the Wipers 32, 33 and 34 as itpassesV under them in the'manner-illustrated in Fig. 6. In diametric opposition to this segment is one designated 'i3-ofv narrower WidthA so asV to haveelectrical engagement only with thel wipers 32 and 33,'but failing because of its narrower Width to engage wiper 34. Between the already described quadrant segmentsare thosedesignated 14 similar to each other and of sucient width only to have electrical engagement with the voutermost wiper 32 vand none withthe intermediate and innermost wipers 33 vand 34. In this way-when one of the three wipers 32, 33 or 34 is established for effectiveness, it' determinesV the numbervof operations per 4hour during which fuel feeding is periodically' stimulated in orderA to sustain fire during bland weather conditions.V This regulation of frequency renders any coal fired .system adaptable to av full'range of solidfuel fire retaining characteristics whereby local supply factors may be practically-reconciled for ideal operation.

The angular spacing of movable contact spring 69 'with respect to each or any of the stationary springs v32,33 and- 34 determines vthe period of bridgem'ent` 'duringr each operating interval.

Thus, on hourly intervals' spring '69 lcooperating springs is smaller and for a smaller interval when the spacing between said springs is relatively greater. The same relationship is true between contact spring 69 and each of the other Contact springs 32 and 33 in respect to half-hourly and quarter-hourly periods of stimulation.

Distributor disk 2'| by virtue of its simple design, not only affords the already described advantages in regulating the performance of the timing controls, but also it is to be noted that through its structural characteristic lends itself to economical fabrication and assembly, The segments '12, 'I3 and 'I4 are preferably punched out as a single disk, placed upon the insulation 21 and secured in position by the imbedded rivets after which the segments are separated by being cut apart on a rotary milling machine which establishes the radial slots This method of construction secures the alignment of the segments with infallible accuracy and minimizes piece-part handling to a profound degree. The slots afford an instantaneous drop-off path for the follower portions 26 of the several springs 32 to 34, 61, 69 and 25 thereby arcing of even an insignificant degree as is characteristic of supervisory voltages is practically eliminated.

Fire pilot regulation as has already been explained constitutes a necessary practice in the solid fuel burning systems because of seasonal and erratic weather demands. In addition, other automatic regulatory practices must be superimposed upon the fire piloting functions without incurring any conditions of interference and preferably without producing undue prolongation such as might be a consequence of additive effects.

In the diagram featured in Fig. 7 a three-wire thermostat control has been illustrated. The thermostat is located in the objective space to be heated and a heat responsive element therein alternatively makes connection between its central terminal |02 and a heat demand terminal |03 or at the heat sufficiency indicating terminal IM. Conductors leading from the aforedescribed terminals to a cable |05 are electrically connected with their respective terminal screws in the re pilot control panel as indicated in Fig. l. The stoker is powered by an electric motol` designated |06 and in the case of a furnace the bonnet space is designed to have its air advanced by an electric fan motor |01 so as to accelerate heat distribution. When a condition of obstruction or overloading of the stoker occurs, means are provided for setting up a contact closing signal and this regulation tained within the symbol |08.

If as a result of unusual rapid consumption of the coal in the hopper, or if through inadvertence the supply is permitted to become depleted, means have been provided in connection with Stoker systems for initiating a signal electrically. This apparatus is symbolized by the reference numeral |09 designated low coal. The manner in which the overload safety feature and the low coal feature tie in with the nre pilot is also portrayed in the wiring diagram Fig. 7. 1

In order to prevent overheating of the nre box under conditions of continuous heat demand, a -thermostat circuit opening apparatus is provided, known as a limit control. This feature has been indicated by the reference numeral Also following an extended period of heat demand followed by a satisfaction signal the trend to overrun is diminished by dissipating heat accumulations in the bonnet under the supervision of a is represented by apparatus con- 6 thermostat device therein provided. This apparatus has been designated by the reference numeral ||2.

The manner in which all of these devices connect with the re pilot control is clearly revealed in the circuit arrangement of Fig. 7. Line voltage originates at a source |I3 and in accordance with good practice is locally safety fused at a junction H4. The service line enters the apparatus at the transformer and relay chamber whereat the voltage is reduced for purposes of the supervisory control circuit. At ||5, however, full line voltage extends to operate the stoker and fan motor as well as at ||6 to operate the heat dissipating fan.

It is to be observed that, particularly in the burning of high coking or sub-marginal coals, continuous operation in response to a prolonged heat demand produces a coke formation in the lire bed commonly referred to as black island or coke trees. An effective method of preventing these formations is to introduce a periodic interruption at regular intervals during such continuous heat demands, and towards this end'the present apparatus has been designed so as to incorporate an invariable interruption interval to occur four times during each hourly cycle. The duration of this interruption may be regulated by carrier 49 which determines the placement of contact spring S7 and in relation to its associated stationary spring 25, and as in the case of the already described adjustment, between spring 69 and its associated springs 32, 33 and 34. The adjustment may be varied between predetermined maximum and minimum intervals preferably not exceeding seven minutes per interruption.

While the present invention has been explained and described with reference to specific embodiments, it will be understood, nevertheless, that numerous modifications and variations may be incorporated without departing from the essential spirit and scope thereof. It is, accordingly, not intended to be limited by the detailed description in the foregoing specication, nor by the specic illustrations in the accompanying drawings except as indicated in the hereunto appended claims.

The invention claimed is:

l. A timing apparatus for re piloting control which comprises in combination, a rotary shaft, a journal support for said shaft having a concentric sleeve portion, members pivotally rotatable upon said sleeve portion and each having an offset contact spring mount and a perpendicularly extending arm, a face panel having a central opening in concentric alignment with said rotary shaft and arcuate slots through which protrude for limited movement said member extending arms, a distributor disc journalled for rotation in said face panel central opening, a slip clutch for coupling said disc to said rotary shaft, said disc carrying a planar alignment of conducting segments on one of its faces divided quadrantally by intersecting radial channel cuts, piloting control contact springs carried by said offset mounts whereby to be rotatable in accordance with the regulation of said perpendicularly extending arms, and stationary contact springs companion to said mount carried springsv for establishing variable bridgement intervals by said disc lconducting segments.

2. The combination set forth in claim 1 in which said conducting segments are at different distances radially and in which said piloting control contact springs are carried on said mounts at correspondingly different radial distances from the disc center.

3. The combination set forth in claim 1 in which said conducting segments are of various radial Widths and in which said piloting control contacts are plural for the purpose of establishing in cooperation with said stationary companion contact springs plural control bridgement intervals.

4. A timing apparatus for fire piloting control which comprises in combination. a rotary shaft synchronously and continuously driven at a predeterminedrate of revolution, a journal support for said shaft having a concentric sleeve portion, a pair of contact regulating members pivotalli7 carried upon said` sleeve portion and each having an offset contact spring mount and a perpendicularly extending arm, a face panel having a central opening in concentric alignment with said rotary shaft and arcuate slots through which protrude for limited movement said pair of contact member perpendicularly extending arms, a distributor disc journalled for rotation in said face panel central opening, a slip clutch for coupling said disc to said rotary shaft, said disc carrying a planar alignment of contact spring conducting segments on one of its faces divided quadrantally by intersection radial channel cuts, piloting control contact springs carried by said oiset mounts whereby to be rotatable in accordance with the regulation of said perpendicular extending arms, a stationary vcontact spring for establishing with said mount carried springs Variably timed intervals of circuit control.

C. RICHARD BOWLAND. LINVILLE H. CRICK, JR.

REFERENCES CITED The following references are of -record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,183,196 vI-Ieany May 16, 1916 1,402,927 Grazier Jan. 10, 1922 1,676,185 Gilchrist et al. July 3, 1928 1,893,365 Hall Jan. 3, 1933 2,125,970 Waters Aug. 9, 1938 2,172,927 Andeen Sept. 12, 1939 2,384,489 Pancher Sept. 11, 1945 FOREIGN PATENTS Number Country Date 123,619 Austria July 10, 1931 

